A binding medium of an existing banknote binding machine is pulled by a track or a clamping mechanism to bind a stack of banknotes to be bound. When the binding medium is pulled by the clamping mechanism, the clamping mechanism is required to be opened quickly and stably, and after being opened, the clamping mechanism is required to stop at a certain position and wait for the binding medium to enter. However, when the current binding medium clamping mechanism stops at the certain position, a retaining force of an actuating device is used to prevent the position of the clamping device from changing in the opening process, which has a high requirement on the actuating device. Further, an additional actuating device is required to open the clamping mechanism, thus the mechanism has a complicated structure and a high economic cost.